#!/usr/bin/env python3
#
# Copyright (c) 2016 Intel, Inc.
#
# SPDX-License-Identifier: GPL-2.0-only
#
# DESCRIPTION
# This module provides parser for kickstart format
#
# AUTHORS
# Ed Bartosh <ed.bartosh> (at] linux.intel.com>

"""Kickstart parser module."""

import os
import shlex
import logging
import re

from argparse import ArgumentParser, ArgumentError, ArgumentTypeError

from wic.engine import find_canned
from wic.partition import Partition
from wic.misc import get_bitbake_var

logger = logging.getLogger('wic')

__expand_var_regexp__ = re.compile(r"\${[^{}@\n\t :]+}")

def expand_line(line):
    while True:
        m = __expand_var_regexp__.search(line)
        if not m:
            return line
        key = m.group()[2:-1]
        val = get_bitbake_var(key)
        if val is None:
            logger.warning("cannot expand variable %s" % key)
            return line
        line = line[:m.start()] + val + line[m.end():]

class KickStartError(Exception):
    """Custom exception."""
    pass

class KickStartParser(ArgumentParser):
    """
    This class overwrites error method to throw exception
    instead of producing usage message(default argparse behavior).
    """
    def error(self, message):
        raise ArgumentError(None, message)

def sizetype(arg):
    """
    Custom type for ArgumentParser
    Converts size string in <num>[K|k|M|G] format into the integer value
    """
    if arg.isdigit():
        return int(arg) * 1024

    if not arg[:-1].isdigit():
        raise ArgumentTypeError("Invalid size: %r" % arg)

    size = int(arg[:-1])
    if arg.endswith("k") or arg.endswith("K"):
        return size
    if arg.endswith("M"):
        return size * 1024
    if arg.endswith("G"):
        return size * 1024 * 1024

    raise ArgumentTypeError("Invalid size: %r" % arg)

def overheadtype(arg):
    """
    Custom type for ArgumentParser
    Converts overhead string to float and checks if it's bigger than 1.0
    """
    try:
        result = float(arg)
    except ValueError:
        raise ArgumentTypeError("Invalid value: %r" % arg)

    if result < 1.0:
        raise ArgumentTypeError("Overhead factor should be > 1.0" % arg)

    return result

def cannedpathtype(arg):
    """
    Custom type for ArgumentParser
    Tries to find file in the list of canned wks paths
    """
    scripts_path = os.path.abspath(os.path.dirname(__file__) + '../../..')
    result = find_canned(scripts_path, arg)
    if not result:
        raise ArgumentTypeError("file not found: %s" % arg)
    return result

def systemidtype(arg):
    """
    Custom type for ArgumentParser
    Checks if the argument sutisfies system id requirements,
    i.e. if it's one byte long integer > 0
    """
    error = "Invalid system type: %s. must be hex "\
            "between 0x1 and 0xFF" % arg
    try:
        result = int(arg, 16)
    except ValueError:
        raise ArgumentTypeError(error)

    if result <= 0 or result > 0xff:
        raise ArgumentTypeError(error)

    return arg

class KickStart():
    """Kickstart parser implementation."""

    DEFAULT_EXTRA_SPACE = 10*1024
    DEFAULT_OVERHEAD_FACTOR = 1.3

    def __init__(self, confpath):

        self.partitions = []
        self.bootloader = None
        self.lineno = 0
        self.partnum = 0

        parser = KickStartParser()
        subparsers = parser.add_subparsers()

        part = subparsers.add_parser('part')
        part.add_argument('mountpoint', nargs='?')
        part.add_argument('--active', action='store_true')
        part.add_argument('--align', type=int)
        part.add_argument('--exclude-path', nargs='+')
        part.add_argument("--extra-space", type=sizetype)
        part.add_argument('--fsoptions', dest='fsopts')
        part.add_argument('--fstype', default='vfat',
                          choices=('ext2', 'ext3', 'ext4', 'btrfs',
                                   'squashfs', 'vfat', 'msdos', 'swap'))
        part.add_argument('--mkfs-extraopts', default='')
        part.add_argument('--label')
        part.add_argument('--use-label', action='store_true')
        part.add_argument('--no-table', action='store_true')
        part.add_argument('--ondisk', '--ondrive', dest='disk', default='sda')
        part.add_argument("--overhead-factor", type=overheadtype)
        part.add_argument('--part-name')
        part.add_argument('--part-type')
        part.add_argument('--rootfs-dir')

        # --size and --fixed-size cannot be specified together; options
        # ----extra-space and --overhead-factor should also raise a parser
        # --error, but since nesting mutually exclusive groups does not work,
        # ----extra-space/--overhead-factor are handled later
        sizeexcl = part.add_mutually_exclusive_group()
        sizeexcl.add_argument('--size', type=sizetype, default=0)
        sizeexcl.add_argument('--fixed-size', type=sizetype, default=0)

        part.add_argument('--source')
        part.add_argument('--sourceparams')
        part.add_argument('--system-id', type=systemidtype)
        part.add_argument('--use-uuid', action='store_true')
        part.add_argument('--uuid')
        part.add_argument('--fsuuid')

        bootloader = subparsers.add_parser('bootloader')
        bootloader.add_argument('--append')
        bootloader.add_argument('--configfile')
        bootloader.add_argument('--ptable', choices=('msdos', 'gpt'),
                                default='msdos')
        bootloader.add_argument('--timeout', type=int)
        bootloader.add_argument('--source')

        include = subparsers.add_parser('include')
        include.add_argument('path', type=cannedpathtype)

        self._parse(parser, confpath)
        if not self.bootloader:
            logger.warning('bootloader config not specified, using defaults\n')
            self.bootloader = bootloader.parse_args([])

    def _parse(self, parser, confpath):
        """
        Parse file in .wks format using provided parser.
        """
        with open(confpath) as conf:
            lineno = 0
            for line in conf:
                line = line.strip()
                lineno += 1
                if line and line[0] != '#':
                    line = expand_line(line)
                    try:
                        line_args = shlex.split(line)
                        parsed = parser.parse_args(line_args)
                    except ArgumentError as err:
                        raise KickStartError('%s:%d: %s' % \
                                             (confpath, lineno, err))
                    if line.startswith('part'):
                        # SquashFS does not support filesystem UUID
                        if parsed.fstype == 'squashfs':
                            if parsed.fsuuid:
                                err = "%s:%d: SquashFS does not support UUID" \
                                       % (confpath, lineno)
                                raise KickStartError(err)
                            if parsed.label:
                                err = "%s:%d: SquashFS does not support LABEL" \
                                       % (confpath, lineno)
                                raise KickStartError(err)
                        if parsed.use_label and not parsed.label:
                            err = "%s:%d: Must set the label with --label" \
                                  % (confpath, lineno)
                            raise KickStartError(err)
                        # using ArgumentParser one cannot easily tell if option
                        # was passed as argument, if said option has a default
                        # value; --overhead-factor/--extra-space cannot be used
                        # with --fixed-size, so at least detect when these were
                        # passed with non-0 values ...
                        if parsed.fixed_size:
                            if parsed.overhead_factor or parsed.extra_space:
                                err = "%s:%d: arguments --overhead-factor and --extra-space not "\
                                      "allowed with argument --fixed-size" \
                                      % (confpath, lineno)
                                raise KickStartError(err)
                        else:
                            # ... and provide defaults if not using
                            # --fixed-size iff given option was not used
                            # (again, one cannot tell if option was passed but
                            # with value equal to 0)
                            if '--overhead-factor' not in line_args:
                                parsed.overhead_factor = self.DEFAULT_OVERHEAD_FACTOR
                            if '--extra-space' not in line_args:
                                parsed.extra_space = self.DEFAULT_EXTRA_SPACE

                        self.partnum += 1
                        self.partitions.append(Partition(parsed, self.partnum))
                    elif line.startswith('include'):
                        self._parse(parser, parsed.path)
                    elif line.startswith('bootloader'):
                        if not self.bootloader:
                            self.bootloader = parsed
                        else:
                            err = "%s:%d: more than one bootloader specified" \
                                      % (confpath, lineno)
                            raise KickStartError(err)